Base assembly for office chair

ABSTRACT

A base assembly of an office chair includes a mounting member, multiple extensions and a bottom disk. The mounting member has multiple installation slots located evenly along the periphery of the mounting member. Each extension has a connection member at the first end thereof so as to be engaged with the installation slot corresponding thereto. The bottom disk is located at the underside of the first end of each of the extensions and has multiple holes and a central hole. Bolts extend through the holes and are connected to the underside of the mounting member to position the first ends of the extensions.

BACKGROUND OF THE INVENTION

(1) Fields of the Invention

The present invention relates to a base assembly for an office chair,and more particularly, to a base assembly composed of two or threeparts.

(2) Descriptions of Related Art

There is a need for most of the users work in the offices to get anoffice chair which provides proper support to the user and makes theuser to be comfortable after being sitting in the chair for whole day. Achair that has poor design and support will cause the user to havemuscles sore and pain due to bad blood circulation. A base assembly is akey part for a chair and the star base is commonly used for the chairs.The star base has a larger contact area with the floor and providesbetter support and balance.

FIG. 1 discloses a conventional base assembly of an office chair andcomprises a base 10 with five extensions 11 extending radially from thebase 10. The five extensions 11 are evenly separated from each other andeach extension 11 has a caster connected thereto. The base 10 has apositioning hole 12 in the center thereof and a support shaft isinserted into the positioning hole 12. The base 10 is integrally formedso as to provide a stable support to the weight of the user. However,the integral base 10 is bulky and occupies a lot of space when packing,storage and transportation.

FIGS. 2 and 3 show the base 20 which is composed of a fixing member 21,a first tube 22 and a second tube 23, wherein the fixing member 21 is aflat board and a connection portion 211 extends centrally from thefixing member 21 so that a support shaft 25 is connected with theconnection portion 211. The fixing member 21 has multiple contactportions 212. The first tube 22 is removably connected to the contactportions 212 and the two ends of the first tube 22 contact the floor.The first tube 22 has a first notch 221 defined in the middle portionthereof, and the second tube 23 has a second notch 231 defined in themiddle portion thereof. The first and second notches 221, 231 areengaged with each other, and the two ends of the second tube 23 contactthe floor. The weight of the user is supported by the fixing member 21and the first and second tubes 22, 23. The first and second notches 221,231 weaken the structural strength of the first and second tubes 22, 23,the first and second tubes 22, 23 are easily deformed or broken at thepositions wherein the first and second notches 221, 231 are located. Thecontact portions 212 are connected to the board-like fixing member 21 bybolts 24 so that the contact portions 212 are easily deformed and thebolts 24 can be loosened.

The conventional base of the office chair is a one-piece structure whichis solid and strong, but it is also bulky and occupies a lot of spacewhen packing, storage and transportation. Although some of theconventional base assembly is composed of individual parts, theconnection is not reliable and is easily broken and deformed, which isnot safe.

The present invention intends to provide a base assembly of an officechair which improves the shortcomings mentioned above.

SUMMARY OF THE INVENTION

The present invention relates to a base assembly of an office chair andis composed of two or three parts. The parts occupy not too much spaceand are easily packed, stored and transported.

The base assembly has a mounting member which is a solid member withthreaded holes so that the five extensions are securely connected to themounting member and are not skew due to weakness of the mounting member.

The openings of the mounting member each are defined by two solid wallswhich can bear lateral force from the extensions connected to themounting member. The openings also make the assembling anddis-assembling steps for the base assembly to be simplified.

The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawingswhich show, for purposes of illustration only, a preferred embodiment inaccordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view to show the conventional integral baseassembly;

FIG. 2 is an exploded view of another conventional base assembly;

FIG. 3 is a cross sectional view showing the conventional base assemblyin FIG. 2;

FIG. 4 is an exploded view of the first embodiment of the base assemblyof the present invention;

FIG. 5 is a perspective view of the first embodiment of the baseassembly of the present invention;

FIG. 6 is a cross sectional view of the first embodiment of the baseassembly of the present invention;

FIG. 7 is a plan view to show the mounting member of the firstembodiment of the base assembly of the present invention;

FIG. 8 is a plan view to show the first embodiment of the base assemblyof the present invention;

FIG. 9 is an exploded view of the second embodiment of the base assemblyof the present invention;

FIG. 10 is a perspective view of the second embodiment of the baseassembly of the present invention;

FIG. 11 is a cross sectional view of the second embodiment of the baseassembly of the present invention, and

FIG. 12 is a plan view to show the second embodiment of the baseassembly of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 4 to 6, the first embodiment of the base assembly ofan office chair of the present invention comprises a mounting member 30,multiple extensions 40 and a bottom disk 50. The mounting member 30 is acylindrical member and has a positioning hole 31 defined centrallytherein, and a shaft 60, such as a gas lift, is inserted in thepositioning hole 31. The shaft 60 supports the seat. Multipleinstallation slots 32 are located evenly along the periphery of themounting member 30. The installation slots 32 each are a T-shaped holewhich has an opening 321 and a curved recess 322. Two sides of eachopening 321 are solid walls 323. The underside of the mounting member 10has multiple threaded holes 324 which are located alternatively relativeto the installation slots 32 and defined in the solid material of themounting member 10. Metal threaded tubes may be inserted into thethreaded holes 324.

There are five extensions 40 each have a connection member 41 connectedto the first end thereof. The connection member 41 is engaged with theinstallation slot 32 corresponding thereto. The connection member 41 ofeach of the extensions 40 is a T-shaped member and has a narrowed neck411 and a plate 412 extending from two sides of the neck 411. The neck411 is located corresponding to the opening 321 of the installation slot32 corresponding thereto. The plate 412 is engaged with the curvedrecess 322 of the installation slot 32 so as to engage the connectionmember 41 with the installation slot 32. The second end of eachextension 40 is connected with a caster. The five extensions 40 may havedifferent colors.

The bottom disk 50 is a ring-shaped disk and has multiple holes 52 and acentral hole 51. Multiple protrusions 53 extend from the bottom disk 50and are evenly separated from each other, the protrusions 53 are locatedalternatively relative to the holes 52. Bolts 54 extend through theholes 52 and are connected to the threaded holes 324 in the underside ofthe mounting member 30 to position the first ends of the extensions 40as shown in FIG. 6.

When in assembling, the connection members 41 of the extensions 40 areengaged with the installation slots 32 of the mounting member 30, andthe necks 411 of the connection members 41 are engaged with the openings321 of the installation slots 32 and the plates 412 are engaged with thecurved recesses 322 of the installation slots 32 to connect theconnection members 41 to the installation slots 32. The bottom disk 50is then positioned at the underside of the first ends of the extensions40. The protrusions 53 of the bottom disk 50 are engaged with the lowerportion of the openings 321 of the installation slots 32. The bolts 54extend through the holes 52 of the bottom disk 50 and are connected tothe threaded holes 324 of the mounting member 30 to secure the bottomdisk 50 to the underside of the mounting member 30, and the first endsof the extensions 40 are therefore positioned.

The base assembly are composed of multiple parts, but the threaded holes324 are located at the solid material of the mounting member 30, and thetwo sides of each opening 321 are two solid walls 323, so that when theconnection members 41 of the extensions 40 are engaged with theinstallation slots 32 of the mounting member 30, the mounting member 30bears the upward force from the connection members 41, and the two solidwalls 323 of the opening 321 bear the lateral forces from the extensions40. The five extensions 40 are well balanced and positioned. The bolts54 are connected to the threaded holes 324 in the solid material canalso bear larger forces to prevent the extensions 40 from being loosenedor tilt.

There are advantages for the first embodiment described above, the baseassembly of the present invention is not a one-piece structure, andcomposed of multiple small parts which are easily stored, packed andtransported, a lot of space is saved. The base assembly is composed ofmultiple parts but the structural strength is reinforced so that thebase assembly does not break. The threaded holes 324 are located in thesolid material of the mounting member 30 can bear larger forces from theextensions 40, not any one of the extensions will be tilt and the bolts54 in the threaded holes 324 do not loose. The two solid walls 323 ofthe opening 321 bear the lateral forces from the extensions 40. The baseassembly is easily assembled and dis-assembled.

FIGS. 9 to 12 show the second embodiment of the present invention,wherein the base assembly of the present invention comprises a mountingmember 70, multiple extensions 80, a bottom disk 90 and a cap 100. Themounting member 70 is a cylindrical member and has a positioning hole 71defined centrally therein, and a shaft 60, such as a gas lift, isinserted in the positioning hole 71. Multiple installation slots 72 areU-shaped slots and located evenly along the periphery of the mountingmember 70 as shown in FIG. 12. The installation slots 72 each have anopening 721 and a curved recess 722. Two sides of each opening 721 aresolid walls 723. The mounting member 70 has recesses 724 and blocks 725formed in the inner periphery thereof. Multiple threaded holes 726 aredefined in the underside of the mounting member 70 and metal threadedtubes may be installed in the threaded holes 726. The threaded holes 726of the mounting member 70 are located alternatively relative to theinstallation slots 72. There are five extensions 80 and each have aconnection member 81 connected to the first end thereof, a caster isconnected to the second end of each extension 80. The five extensions 80may have different colors.

A cap 100 is connected to the top of the mounting member 70 and hasmultiple concavities 101 and insertions 102 on the underside thereof.The blocks 725 are engaged with the concavities 101, and the insertions102 are engaged with the recesses 724. The connection members 81 of theextensions 80 each have a narrowed neck 811 and a plate 812 extends fromtwo sides of the neck 811. The plates 812 are slightly larger than theconnection members 81 and are engaged with the curved recesses 722 ofthe installation slots 72.

The cap 100 has a passage 104 defined centrally therethrough. The cap100 has a bottom ring 103 extending from the underside thereof. Thebottom disk 90 has a top ring 93 extending from the top thereof, thebottom ring 103 is engaged with notches in respective tops of the necks811 of the connection members 81 of the extensions 80. The top ring 93is engaged with notches in respective bottoms of the necks 811 of theconnection members 81 of the extensions 80.

The bottom disk 90 is a ring-shaped disk and positioned at the undersideof the first ends of the extensions 80. The bottom disk 90 has a centralhole 91 and multiple holes 92 in the periphery thereof. Bolts 84 extendthrough the holes 92 of the bottom disk 90 and are connected to thethreaded holes 726 of the mounting member 70 to secure the bottom disk90 and the extensions 80 to the underside of the mounting member 70.

When in assembling, the connection members 81 of the extensions 80 areengaged with the installation slots 72 of the mounting member 70, andthe plates 812 are engaged with the curved recesses 722 of theinstallation slots 72. The blocks 725 of the mounting member 70 areengaged with the concavities 101 of the cap 100. The insertions 102 areengaged with the recesses 724. The bottom ring 103 is engaged withnotches in respective tops of the necks 811 of the connection members 81of the extensions 80 to position the cap 100 to the top of the mountingmember 80, and the bottom disk 90 is connected to the undersides of theconnection members 81. The top ring 93 is engaged with notches inrespective bottoms of the necks 811 of the connection members 81 of theextensions 80. Bolts 84 extend through the holes 92 of the bottom disk90 and the threaded holes 726 of the mounting member 70, to secure thebottom disk 90 to the underside of the mounting member 70 and the firstends of the extensions 80.

The base assembly of the second embodiment has five extensions 80 andthe five extensions 80 are well balanced and positioned. The bolts 84are connected to the threaded holes 726 in the solid material can alsobear larger forces to prevent the extensions 80 from being loosened ortilt. The bolts 84 do not loose. The use of the cap 100 reinforces theconnection of the extensions 80.

There are advantages for the second embodiment described above, the baseassembly of the present invention is not a one-piece structure, andcomposed of multiple small parts which are easily stored, packed andtransported, a lot of space is saved. The base assembly is composed ofmultiple parts but the structural strength is reinforced so that thebase assembly does not break. The threaded holes 726 are located in thesolid material of the mounting member 70 can bear larger forces from theextensions 80, not any one of the extensions will be tilt and the bolts84 in the threaded holes 726 do not loose. The two solid walls of theopening 721 bear the lateral forces from the extensions 80. The baseassembly is easily assembled and dis-assembled.

While we have shown and described the embodiment in accordance with thepresent invention, it should be clear to those skilled in the art thatfurther embodiments may be made without departing from the scope of thepresent invention.

What is claimed is:
 1. A base assembly comprising: a mounting memberhaving multiple installation slots which are located evenly along aperiphery of the mounting member, a positioning hole defined centrallyin the mounting member and a shaft inserted in the positioning hole;multiple extensions each having a connection member connected to a firstend thereof, the connection member being engaged with the installationslot corresponding thereto, and a bottom disk located at an underside ofthe first end of each of the extensions and having multiple holes, boltsextending through the holes and being connected to an underside of themounting member to position the first ends of the extensions.
 2. Thebase assembly as claimed in claim 1, wherein the underside of themounting member has multiple threaded holes which are locatedalternatively relative to the installation slots and defined in a solidmaterial of the mounting member, the installation slots each are aT-shaped hole which has an opening and a curved recess, two sides ofeach opening are solid walls, the connection member of each of theextensions is a T-shaped member and has a narrowed neck and a plateextending from two sides of the neck, the bottom disk has multipleprotrusions which are located alternatively relative to the holes. 3.The base assembly as claimed in claim 1, wherein a cap is connected to atop of the mounting member and has a passage defined centrallytherethrough, the cap has multiple concavities and insertions on anunderside thereof, the mounting member has multiple threaded holesdefined in an underside thereof and the threaded holes of the mountingmember are located alternatively relative to the installation slots,each installation slot has an opening and a curved recess, two sides ofthe opening are solid walls, the mounting member has recesses and blocksformed in an inner periphery thereof, the blocks are engaged with theconcavities, the insertions are engaged with the recesses, theconnection members of the extensions each have a narrowed neck and aplate extends from two sides of the neck, the plates are larger than theconnection members and are engaged with the curved recesses of theinstallation slots.
 4. The base assembly as claimed in claim 3, whereinthe cap has a bottom ring extending from the underside thereof, thebottom disk has a top ring extending from a top thereof, the bottom ringis engaged with notches in respective tops of the necks of theconnection members of the extensions, the top ring is engaged withnotches in respective bottoms of the necks of the connection members ofthe extensions.